Totally agree that what u describe is unacceptable! There seem to be an increasing number of folks that don't really know HOW to camp or don't care about anyone else in the park. I have much respect for those parents who ARE trying to instill etiquette in their kids. There just is no excuse for the rude people cutting thru sites!
Last year I was run off a lake beach when unruly, whistle blowing brats ran up scaring the******out of my dog (leashed). Grandparents were supervising, totally oblivious, i begged the kid to stop the whistle in order to get my dog off the beach. And yes, there was plenty of space for their family group but they set up chairs practically on top of my beach umbrella. Nobody else was on the beach!